Prevalence of antibodies to selected Leptospira serovars in swine from Poland

Leptospirosis is a worldwide zoonotic disease caused by pathogenic serovars of Leptospira sp. The disease in swine is mainly transmitted by contact with infected urine, blood, tissues, organs, contaminated water and feed. Leptospirosis can be spread by rodents or by direct contact of infected pigs. Clinical symptoms such as abortion, stillbirths and sometimes infertility are the most often observed consequences of Leptospira sp. infection in swine. They cause serious economic losses and may pose a threat to farm staff taking care of the animals. The aim of the study was to examine the seroprevalence of Leptospira sp. infections in Polish swine population.

A total of 22883 swine serum samples (up to 400 serum samples for one province per year) were collected from 2011 to 2015 in the monitoring program from all 16 provinces of Poland. All the serum samples were tested by microscopic agglutination test (MAT) with the panel of 6 serovars representative of 6 serogroups, most often found in swine population in Poland: Icterohaemorrhagiae (RGA), Grippotyphosa (Moskva V), Sejroe (M84), Tarassovi (Perepelicyn), Pomona (Pomona), Canicola (Hond Utrecht IV). The minimum sera dilution was 1:100.

During the last 5 years the seroprevalence of Leptospira in swine was as follows: 2.68%, 1.47%, 2.02%, 1.42% and 1.32%, respectively. Yearly, the highest percentages of seropositive swine serum samples, were found in the north and south part of the country, while a low seroprevalence was observed in the central and western regions of Poland. The most common serovars between 2011-2015 were: Pomona (1.01%, 0.39%, 0.62%, 1.02% and 1.13%, respectively) and Sejroe (1.12%, 0.8%, 1.05%, 0.36% and 0.18%, respectively).

Similar studies conducted in 2009-2010 showed a slightly lower seroprevalence, of around 1%, with regard to the tested Leptospira serovars. Pomona and Sejroe have been constantly, the most common serovars isolated from pigs in Poland. Our observations from recent two years confirm that serological reactions with serovar Sejroe in pigs in Poland have a decreasing tendency. The occurrence of other Leptospira serovars is marginal. Although west and north-west part of the country represent a high pig population density and an intensive pig production system, our investigations from the last years indicate a low seroprevalence to 6 tested serovars. Described above regions with the highest Leptospira seroprevalence represent more extensive pig production systems.

Disclosure of Interest: None Declared.